What Is The Sleeper Stretch?
The sleeper stretch has been around almost as long as baseball. To perform the sleeper stretch, one lays on the same side as their throwing shoulder, brings that shoulder to 90 degrees of flexion so it is perpendicular to their body, and then internally rotates the shoulder. Athletes at all levels of the sport use it, but is it really helping them? Here, I will discuss why most people should avoid the sleeper stretch.
Most athletes that utilize the sleeper stretch are doing so to address a lack of internal rotation at the shoulder. A lack of internal rotation greater than 20 degrees compared to the other shoulder is termed glenohumeral internal rotation deficit, or GIRD. This was originally viewed as an injury, but it is now used more as a measurement assessment, meaning that GIRD alone is no longer a bad thing.
After years and years of throwing a baseball, the body eventually adapts to the high torque generated from a throwing motion. This adaptation results in a loss of internal rotation at the shoulder, with an equal or greater gain in external rotation to allow the body to achieve the necessary motion to throw a baseball. With this in mind, assessment of the shoulder should be focused on total arc of motion, as opposed to internal rotation and external rotation individually.
For example, an athlete may have 65 degrees of internal rotation and 115 degrees of external rotation in their throwing shoulder while having 85 degrees of internal rotation and 95 degrees of external rotation in their non-throwing shoulder. While this athlete does have GIRD in their throwing shoulder, their total arc of motion is equal on both sides, which is normal for a baseball player. Even if they have an extra 10-20 degrees of motion in their total arc, that can be a typical finding in a thrower. Now if this athlete was to have 65 degrees of internal rotation and 145 degrees of external rotation in their throwing shoulder, that could be a red flag.
Having an extra 30 degrees of motion compared to the non-throwing shoulder could be a sign of hypermobility, which may lead to injury. For these reasons, it is important to take note of the total arc of motion instead of solely focusing on addressing the internal rotation deficit. By stretching a shoulder that is already hypermobile to begin with, it will just make the shoulder more hypermobile.
The Posterior Capsule Isn’t The Problem
In addition to the changes in motion at the shoulder, the extreme torque generated from the mechanics of throwing places a significant amount of stress on the anterior capsule (front part) of the shoulder, causing anterior instability. This is another typical finding in the shoulder of a thrower. This is typically not a problem as long as the shoulder musculature is strong and durable. However, for people that have GIRD, the sleeper stretch is commonly used to target the posterior capsule (back part) and regain internal rotation. Stretching out the back of the shoulder when the front of the shoulder is already unstable will now make an unstable shoulder even more unstable.
Shoulders with such extreme instability can cause several things to happen. Other structures in the shoulder may now be more heavily relied upon to stabilize the shoulder, such as the labrum; shoulder musculature, such as the rotator cuff and biceps, may have to work harder to keep the shoulder stable; the high level of instability in the shoulder may allow it to go to ranges that the body cannot handle. If any of these things happen, this makes the athlete more susceptible to rotator cuff, labrum, and biceps injuries.
For many throwers, the posterior capsule isn’t the problem. It may appear so due to the loss of internal rotation, but the reason for the loss of internal rotation is the body just adapting to the forces from throwing.
Not A Good Position For The Shoulder
In addition to potentially making an unstable shoulder even more unstable, the stretch position is not a friendly position for the shoulder. The sleeper stretch puts the shoulder in the same position as the Hawkins-Kennedy impingement test. This test is used to see if there is an injury to one of the tendons of the rotator cuff or one of the bursae (fluid-filled sacs) in the shoulder. The only difference is that the patient is side-lying for the sleeper stretch while they are seated or supine for the Hawkins-Kennedy test.
In anatomical neutral (hands by your side with your palms facing forward) the subacromial space, defined as the space between the acromion and humeral head where the supraspinatus tendon and subacromial bursa reside, measures on average 10mm, or about 0.4in. To give a comparison, 10mm is slightly larger than the thickness of an iPhone. The average thickness of the supraspinatus tendon in a healthy individual is about 6mm, with the average thickness of the subacromial bursae being about 1mm. This leaves only a few millimeters of free space in a normal healthy shoulder when the shoulder is at rest. When the shoulder is flexed to about 90 degrees, just as it is when performing the sleeper stretch, the space closes down by about 3mm, meaning that the subacromial space is now about the size of the structures that run through it. By internally rotating the shoulder once it is flexed, this now shrinks the space further, causing the supraspinatus tendon and the subacromial bursa to become compressed. For a thrower who most likely has some inflammation going on already, compressing an aggravated tendon will not do them any good.
Now suppose someone truly has a tight posterior capsule that needs to be addressed. In that case, there are safer and more effective alternatives. The best substitute for the sleeper stretch is the cross-body stretch. In a study on 54 subjects, the cross-body stretch resulted in an average increase of 20 degrees of internal rotation. In contrast, the sleeper stretch resulted in an average increase of only 12 degrees. The cross-body stretch results in greater gains in motion while keeping the shoulder in a safe position.
The cross-body stretch can be done in several ways; it can be done independently or done by another individual. It can be done seated, standing, supine, or side-lying when doing the stretch independently. To best stretch the posterior capsule, the shoulder blade (scapula) will need to be stabilized to isolate the posterior capsule. If the shoulder blade is not stabilized, the stretch will instead focus on back muscles such as the rhomboids and mid traps instead of stretching the posterior capsule. The shoulder blade can be stabilized by leaning against a pillar or corner of a wall with the outside of the shoulder blade and then performing the stretch. The best way to do this stretch is to have another individual stabilize the shoulder blade. It is easiest if the person being stretched is supine. To do this, lift the individual’s arm to 90 degrees of flexion, pin down the outside of the shoulder blade with one hand, and use the other hand to bring the individual’s arm across their body. This stretch can be done anywhere from 20-30s for 2-4 sets.
- Mcclure, Philip, et al. “A Randomized Controlled Comparison of Stretching Procedures for Posterior Shoulder Tightness.” Journal of Orthopaedic & Sports Physical Therapy, vol. 37, no. 3, 2007, pp. 108–114., doi:10.2519/jospt.2007.2337.
- Kim, Kyeongwon, et al. “Ultrasound Dimensions of the Rotator Cuff and Other Associated Structures in Korean Healthy Adults.” Journal of Korean Medical Science, The Korean Academy of Medical Sciences, Sept. 2016, www.ncbi.nlm.nih.gov/pmc/articles/PMC4974191/.
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- Hughes, P.C., et al. “Measurement of Subacromial Impingement of the Rotator Cuff.” Journal of Science and Medicine in Sport, Elsevier, 18 Aug. 2011, www.sciencedirect.com/science/article/pii/S1440244011001198.